Compressor Housing for Use at Low Temperatures

ABSTRACT

The invention relates to a turbo machine comprising a housing. Said turbo machine is designed especially as a turbo compressor for use at low temperatures, the housing preferably being made of a cold-resistant material that has a martensitic structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2006/069753, filed Dec. 15, 2006 and claims the benefit thereof. The International Application claims the benefits of European application No. 05027971.0 filed Dec. 20, 2005, both of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a turbomachine, especially compressors or turbocompressors for use at low temperatures, the turbomachine comprising a housing.

BACKGROUND OF THE INVENTION

Such turbomachines with housings are known. Especially housings of compressors or turbocompressors must be designed to withstand high internal pressure. It is known in this respect to use materials, especially low-temperature steels, with an austenitic crystal structure to produce the housing for very low operating temperatures (<−120° C. ), the low-temperature steels with an austenitic crystal structure disadvantageously having very low strength. For this reason, current housings of compressors or turbocompressors for use at low temperatures are made with relatively great wall thicknesses, to be able to withstand the relatively high internal pressure with a very low strength of the material.

Since the austenitic steels also disadvantageously have low thermal conductivity and a high coefficient of thermal expansion, there is also the risk of great temperature gradients within the housing and the risk of thermal stresses even to the extent of permanent plastic deformations.

The International Patent Application WO 99/32837A already discloses a housing of a pump for low-temperature liquids comprising a low-temperature cast steel of martensitic structure with a low nickel content. An Internet article (http://www.acipco.com) already discloses various alloys that also represent the composition of the specific steel ASTM A 352, LC9.

SUMMARY OF INVENTION

The invention is based on the object of improving a housing, especially a housing for compressors, with preference for turbocompressors for use at low temperatures, by simple means to the extent that the housing can be produced with lower wall thicknesses even in the case of very low operating temperatures.

According to the invention, the object is achieved by the housing consisting of a low-temperature material with a martensitic structure.

DETAILED DESCRIPTION OF INVENTION

It is favorable for the purposes of the invention if the housing consists of a low-temperature cast steel, it expediently being provided that the housing consists of a low-temperature cast steel with a nickel content of 8.5 to 10%.

The material with the designation ASTM A 352 LC 9 has proven to be particularly suitable for this. Of course, other low-temperature cast steels with a high nickel content are also suitable.

According to the invention, however, the object is also achieved by using a low-temperature material with a martensitic structure for producing a turbocompressor housing for use at low temperatures, the material ASTM A 352 LC 9 being suitable here with preference.

Low-temperature cast steels with a high nickel content are suitable in particular for low temperatures down to −196° C. On account of the advantageous alloy composition, the structure of nickel-alloyed steels is martensitic, having higher 0.2% tensile yield strengths, lower thermal expansions and higher thermal conductivity in comparison with steels with an austenitic crystal structure.

The higher tensile yield strength advantageously permits lower wall thicknesses of the housing, whereby less housing material is required, so that the costs for producing the housing are lowered considerably. Altogether, the combination of properties of low-temperature cast steels with a high nickel content, especially the material ASTM A 352 LC 9, has the effect that better temperature gradients are achieved and thermal stresses are reduced, whereby the risk of plastic deformations is eliminated. 

1-6. (canceled)
 7. A turbocompressor housing for use at low temperatures, comprising: a housing comprised of a low-temperature material having a martensitic structure.
 8. The turbocompressor housing as claimed in claim 7, wherein the housing consists of a low-temperature cast steel.
 9. The turbocompressor housing as claimed in claim 8, wherein the housing consists of a low-temperature cast steel with a nickel content of 8.5 to 10%.
 10. The turbocompressor housing as claimed in claim 9, wherein the housing consists of the material ASTM A 352 LC
 9. 11. The turbocompressor housing as claimed in claim 10, wherein the housing is a compressor housing for use at low temperature.
 12. The turbocompressor housing as claimed in claim 11, wherein the housing is a compressor housing of a turbocompressor for use at low temperature. 